In an automobile body, for example, a front pillar and a side sill are each a complex of skeletal components. The front pillar is arranged on a front side of the body, extending in a vertical direction. The side sill is arranged in a lower part of the body, extending in a front-back direction. A lower end portion of the front pillar and a fore end portion of the side sill are coupled to each other. Here, for a front pillar, a structure divided into upper and lower parts may be employed. In this case, a skeletal component complex as the upper part of the structure is called a front pillar upper, and a skeletal component complex as the lower part is called a front pillar lower. A lower end portion of the front pillar upper and an upper end portion of the front pillar lower are coupled to each other.
The front pillar lower includes, for example, a front pillar lower outer (hereafter, also simply referred to as an outer), a front pillar lower inner (hereafter, also simply referred to as an inner), and a front pillar lower reinforcement (hereafter, also simply referred to as a reinforcement), as skeletal components. The outer is arranged on an outer side in a car-width direction. The inner is arranged on an inner side in the car-width direction. The outer and the inner are coupled to each other, forming a closed section all over the front pillar lower in a longitudinal direction. The reinforcement is arranged between the outer and the inner to improve the strength of the front pillar lower. Among them, the outer is bent into an L shape along its longitudinal direction, and has a hat-shaped cross section all over the outer in its longitudinal direction.
FIG. 1A and FIG. 1B are schematic diagrams illustrating an example of a front pillar lower outer as a skeletal component. In these drawings, FIG. 1A is a plan view, and FIG. 1B is a cross sectional view taken along a line A-A of FIG. 1A. For ease of understanding the shape of the front pillar lower outer, in FIG. 1A, a side on which the front pillar lower outer is coupled to a side sill is denoted by reference character S, and a side on which the front pillar lower outer is coupled to a front pillar upper is denoted by reference character U. In addition, in FIG. 1A, a forward side in a traveling direction of an automobile is denoted by reference character F, and a rearward side in the traveling direction is denoted by reference character B. In FIG. 1B, an inward side in a car-width direction is denoted by reference character I, and an outward side in the car-width direction is denoted by reference character O.
As illustrated in FIG. 1A, a front pillar lower outer 10 includes a bent portion 13 that is bent into an L shape along the longitudinal direction (see a zone enclosed by a chain double-dashed line in FIG. 1A), and a first region 14 and a second region 15 that are connected to each of the opposite ends of the bent portion 13. The first region 14 extends in a straight manner from the bent portion 13 toward the rearward side B in the traveling direction of the automobile, and is coupled to the side sill. The second region 15 extends in a straight manner upward from the bent portion 13, and is coupled to the front pillar upper.
In addition, as illustrated in FIG. 1B, the cross-sectional shape of the outer 10 is in a hat shape all over the outer 10 in its longitudinal direction, namely, all over the outer 10 from the side U on which the outer 10 is coupled to the front pillar upper to the side S on which the outer 10 is coupled to the side sill. For this reason, the bent portion 13, the first region 14, and the second region 15 constituting the outer 10 each include a top panel portion 10a, a first vertical wall portion 10b, a second vertical wall portion 10c, a first flange part 10d, and a second flange part 10e. The first vertical wall portion 10b is connected to the entirety of a side portion that is the inside of the bending of either side portions of the top panel portion 10a. The second vertical wall portion 10c is connected to the entirety of a side portion that is the outside of the bending of either side portions of the lop panel portion 10a. The first flange part 10c1 is connected to the first vertical wall portion 10b. The second flange part 10e is connected to the second vertical wall portion 10c. 
The front pillar lower is a skeletal component complex assumed to receive a collision load from the forward side of the body. For this reason, the front pillar lower outer 10 is a skeletal component assumed to receive a collision load along an extending direction of the first region 14 coupled to the side sill.
Japanese Patent Application Publication No. 2011-37291 (Patent Literature 1), Japanese Patent No. 5103959 (Patent Literature 2), and Japanese Patent Application Publication No. 2013-141928 (Patent Literature 3) disclose prior arts relating to the front pillar. In a front pillar of Patent Literature 1, on an inner side in a car-width direction of a pillar outer portion (equivalent to the outer) constituting a lower part in a vertical direction, a pillar reinforcing member (equivalent to the reinforcement) is attached. The pillar reinforcing member is provided in its fore portion with a high-strength portion having a strength higher than those of the other portions. Patent Literature 1 describes that this makes it possible to secure a strength required against a collision load from a forward side of a body while reducing the weight of the front pillar.
Front pillars of Patent Literature 2 and Patent Literature 3 have closed section structures. In the front pillar of Patent Literature 2, a reinforcement is constituted by an upper portion, a center portion attached on a lower side of the upper portion, and a lower portion attached on a lower side of the center portion. The attachment between the upper portion and the center portion is accomplished with end portions of both the portions overlapped. This is also the case with the attachment between the center portion and the lower portion. The bonding strength of the attachment between the center portion and the lower portion is set to be lower on a fore side than on a rear side. Patent Literature 2 describes that this makes it possible to improve the productivity of reinforcements even in the case where the reinforcements are produced from a high-tensile steel plate.
In the front pillar of Patent Literature 3, guiding means is provided by making use of a reinforcement. The guiding means has an inclined surface at a position facing a front wheel of an automobile. At the time of small offset collision, the inclined surface guides the front wheel toward the rear outer side of a body. Patent Literature 3 describes that this makes it possible to suppress deformation of the front pillar effectively while securing the stiffness of the front pillar at the time of small offset collision.